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Brandon ThomasandClaude Opus 5.5
dae90e9a7b
Own T.81 encoder: Annex K tables, JFIF YCbCr 4:4:4/4:2:0 + gray, EXIF/XMP/ICC segments, bands of MCU rows separated by RSTn so entropy coding runs on all cores. Per-core speed matches jpeg-encoder at 4:4:4 (225 vs 237 ms on 24 MP, single thread); with all cores 24 MP encodes in ~130 ms vs ~500–800 ms (loaded machine). Output decodes with jpeg-decoder and zune-jpeg (odd sizes tested); same-or-smaller files at equal/higher PSNR. 4:2:2 keeps jpeg-encoder. Bench: crates/codecs/examples/jpeg_bench.rs. Co-Authored-By: Claude Opus 5.5 <[email protected]>
62 lines
2.3 KiB
Rust
62 lines
2.3 KiB
Rust
//! Compare the parallel JPEG encoder with `jpeg-encoder` (size, time, PSNR):
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//! `cargo run --release -p lightcraft-codecs --example jpeg_bench [image]` (default: 6000×4000 synthetic).
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use lightcraft_codecs::ChromaSubsampling;
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use std::time::Instant;
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fn psnr(a: &[u8], b: &[u8]) -> f64 {
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let mse = a.iter().zip(b).map(|(x, y)| (*x as f64 - *y as f64).powi(2)).sum::<f64>() / a.len() as f64;
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10.0 * (255.0f64.powi(2) / mse.max(1e-9)).log10()
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}
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fn best<T>(n: usize, mut f: impl FnMut() -> T) -> (T, f64) {
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let mut out = None;
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let mut t = f64::MAX;
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for _ in 0..n {
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let s = Instant::now();
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let r = f();
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t = t.min(s.elapsed().as_secs_f64() * 1e3);
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out = Some(r);
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}
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(out.unwrap(), t)
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}
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fn main() {
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let (w, h, rgb) = match std::env::args().nth(1) {
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Some(p) => {
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let img = image::open(p).expect("open").to_rgb8();
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(img.width() as usize, img.height() as usize, img.into_raw())
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}
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None => {
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let (w, h) = (6000, 4000);
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let mut v = Vec::with_capacity(w * h * 3);
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for y in 0..h {
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for x in 0..w {
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let t = (((x as f32 / 37.0).sin() * (y as f32 / 23.0).cos()) * 0.5 + 0.5) * 255.0;
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v.extend_from_slice(&[(x * 255 / w) as u8, t as u8, ((x ^ y) & 0xff) as u8]);
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}
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}
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(w, h, v)
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}
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};
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for (sub, js) in
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[(ChromaSubsampling::S444, jpeg_encoder::SamplingFactor::R_4_4_4), (ChromaSubsampling::S420, jpeg_encoder::SamplingFactor::R_4_2_0)]
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{
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let (ours, t_ours) = best(5, || lightcraft_codecs::jpeg_par::encode(&rgb, w, h, 3, 90, sub, &[]));
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let (theirs, t_theirs) = best(3, || {
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let mut out = Vec::new();
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let mut e = jpeg_encoder::Encoder::new(&mut out, 90);
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e.set_sampling_factor(js);
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e.encode(&rgb, w as u16, h as u16, jpeg_encoder::ColorType::Rgb).unwrap();
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out
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});
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let dec = |b: &[u8]| jpeg_decoder::Decoder::new(b).decode().unwrap();
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println!(
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"{w}x{h} {sub:?} q90: parallel {t_ours:.0} ms, {} KB, PSNR {:.2} dB | jpeg-encoder {t_theirs:.0} ms, {} KB, PSNR {:.2} dB",
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ours.len() / 1024,
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psnr(&rgb, &dec(&ours)),
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theirs.len() / 1024,
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psnr(&rgb, &dec(&theirs))
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);
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}
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}
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